TCRαβ CD4-CD8-双阴性 T (DNT) 细胞是外周血中的少数群体，其作用主要在炎症和自身免疫中讨论。然而，DNT细胞在肿瘤微环境中的功能仍有待阐明。我们研究了它们的特征、可能的起源和在结直肠癌组织及其相应的肿瘤引流淋巴结中的功能。我们发现，与相应的淋巴结相比，肿瘤组织中的 DNT 细胞显着富集，特别是在 T 细胞浸润较低的肿瘤中。对CD4 T、CD8 T和DNT细胞的T细胞受体（TCR）序列分析表明，在DNT细胞中检测到的TCR序列在CD8 T细胞中发现，但在CD4 T细胞中很少发现，这表明部分DNT细胞可能是起源于CD8 T细胞。通过对 DNT 细胞的单细胞转录组分析，我们发现 DNT 细胞簇表现出与中央记忆 CD8 T 细胞相似的表型，且效应器和耗竭标记物表达较低，揭示了一些特定的基因表达模式，包括较高的 GZMK 表达。此外，在流式细胞术分析中，我们发现DNT细胞失去了细胞毒性介质的产生。这些发现意味着 DNT 细胞可能在肿瘤微环境中充当抗肿瘤免疫反应的负调节因子。© 2024 作者。经泰勒许可出版

TCRαβ+ CD4- CD8- double-negative T (DNT) cells are minor populations in peripheral blood, and their roles have mostly been discussed in inflammation and autoimmunity. However, the functions of DNT cells in tumor microenvironment remain to be elucidated. We investigated their characteristics, possible origins and functions in colorectal cancer tissues as well as their corresponding tumor-draining lymph nodes. We found a significant enrichment of DNT cells in tumor tissues compared with their corresponding lymph nodes, especially in tumors with lower T cell infiltration. T cell receptor (TCR) sequence analysis of CD4+ T, CD8+ T and DNT cells indicated that TCR sequences detected in DNT cells were found in CD8+ T cells, but rarely in CD4+ T cells, suggesting that a part of DNT cells was likely to be originated from CD8+ T cells. Through a single-cell transcriptomic analysis of DNT cells, we found that a DNT cell cluster, which showed similar phenotypes to central memory CD8+ T cells with low expression of effector and exhaustion markers, revealed some specific gene expression patterns, including higher GZMK expression. Moreover, in flow cytometry analysis, we found that DNT cells lost production of cytotoxic mediators. These findings imply that DNT cells might function as negative regulators of anti-tumor immune responses in tumor microenvironment.© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.